Rubber article and method of making same



Patented Dec. 8, 1931 UNITED STATES PATENT OFFICE JAMES w. SCHADE, F xnon, AN'DEARLAN L. TRUMBULL, or HUDSON, OHIO, AS-

SIGNORS TO THE B. r. GOODRICH COMPANY, or NEW YORK, N. Y., A CORPORATION or NEW YORK RUBBER- ARTICLE AND METHOD MAKING SAME No Drawing.

This invention relates to the production of articles directlyffrom aqueous dispersions to a crushing and kneading action,known as 10 masticatlon; then, there is admixed withthe plastic broken-down rubber, fillers, pigments, vulcanizing agents and other compounding ingredients. These mixtures are then. subjected to such' further working and shaping as the nature of the article to be made may require.

It has also been proposed to form articles directly from latex, either in its natural state or concentrated or admixed with thickening and/or compounding ingredients, as by dipping, spraying, spreading, molding, extruding, electrolytic deposition and the like. This method produces a structure in which the rubber globules ofthe natural latex are not ruptured and their identity destroyed, as in mastication, and the resulting rubber structure possesses a texture which differs from that of rubber which has been subjected to mastication. 'F or example, masticated rubber before its vulcanization possesses a much greatertack or stickiness than does rubber obtained directly from latex, while the latter, when vulcanizedtis far superior in tensilestrength, durability and other important characteristics.

It is the'purpose of this inventionto utilize these differing properties of masticated rubber and of rubber produced from latex without masticationto produce rubber products having combined therein the desirable properties both of latex rubber and of masticated rubber, and thus to make rubber products materially difiering trom,and superior for many purposes to, anyrubber products heretofore available in the industry.

The present invention consists in modifying the properties of products made as hereinabove described by utilizing an admixture of a natural latex with its unruptured rubber globules andwithan artificial aqueous disper- Application filed August 24, 1928. Serial No. 301,944.

sion of a plasticized crude or vulcanized rubber. The dispersions may be in a vulcanized or unvulcanized condition, concentrated or compounded with other ingredients in any way desired, and subjected to such purifying or cleaning action as may be necessary or desirable.

In one embodiment of our invention, rubber latex is mixed with an artificial aqueous dispersion prepared from a plasticized 01' masticated crude or vulcanized rubber, to produce a dispersion containing intimately and uniformly admixed original rubber globules and finely divided masticated rubber particles. This mixed dispersion may, either with or Without further treatment, be employed in the production of rubber articles directly therefrom, which articles will be composed. of the homogeneously arranged unruptured rubber globules and finely divided plasticized rubber particles. By suitably regulating the proportions of the latex and the aqueous dispersion of masticated rubber, the properties of the rubber articles produced directly from a mixed latex and rubber dispersion can be varied to a considerable'extent.

The aqueous dispersions of plasticized rubber we prefer to employ are produced by dispersing plasticizcd rubber in an aqueous medium in the presence of a hydrophilic colloid, such as glue, gelatin, casein, gum arabic and the like, by mastication, with the gradual addition of water until a plastic mass is :formed in which the rubber is the dispersed phase and the hydrophilic colloid is the continuous phase. This plastic mass is 'then diluted with water to such a degree as to produce when mixed with latex a liquid body of desired consistency.

be particularly advantageous in the direct production of formed articles therefrom by electro-deposition' upon' an anodic body.

This is shown in the three following experi- 9 The mixed dispersions have been found to I ulcanized rubber.

and an aqueous dispersion of a plasticized In each case, the latex or latex mixture was treated by adding thereto in the formof an aqueous dispersion zinc stearate 1.5- per :cent, sulfur 3- per cent.,,0rganic. accelerator 03 per l-cen't. .andantioxidant 0.75 per cent. based on the Weight of the solid content of the latex or latex mixture.

Eaeh of the compositions,A,-B,and wasplaced in an'electroph oretic apparatus and v a layer of a rubber composition deposited therefrom'by an electric current of suitable density (about 0.6 amperes per sq. cm'.) upon a metallic anode to a thicknessoi about onesixteenth of an inch. The "deposited rubber composition was in each; case stripped from the anode, dried and Vulcanizedby subjecting itto heat, asin an oven maintained at 275 'F. The results oftests of these products'are shown, in the iollowingtablei ,1;

V Sir-e88 seam "M I pouiids poi sq fi'iaf "an admin elongat ions. 1

s Elongation a a A: a B Ci I, 288 281 489 t 575 492 771' 985 I 1107 1363 1939: 2265 2163 800 3212 3121. 3200 Elongation at bre A v 890% ,775% 815% Resistance to tear at optimum cure 14 18 .25

The resulting product' wa's each of the cases B and C smooth and dense and exhibits tensile strengthcomparablewith latex rubber,-while the sheets are of anerv ier structure than is obtainable With-'mill mix rubber; The products B and G also exhibit properties superiorvto those'foif product A, injthat (1)' in the uncured state the sheet is much ta'cliier' and adheres better to itself, as in'splicin'g, or to other objects; the V111 caniaedsheet has a higher chafing resistance and (3) themaximum' tear resistanceand the maximum tensile occur at the same degree of vulcanization (optimum cure) ,Wh-ile in latex rubber the tear resistance'gtallsofi' asthe'optimunicure is approached. In fact, the properties of the above described prod'ucts'B andG are superior in manyirespects to latex rubber A and to mill-mixsheetsmade ac cording to thecommon' practice I in j rubber factories." l

' Q 'It isto'be understood thisinvention contemplates the productionf'ofrubber artie icle r e m latex, an i per e i a t c The. term spreading, molding, and other Well-known processes? j 3. They-herein described comprises plasticizing a ,c0agulated rubber, 1, I

canizing the articles]:

Ffrubberi nerem emple edf is. inl dients; The term latex is defined for the purpose of this application as the natural milky-juice of laticiferous or rubber plants, Whether or not concentrated or diluted and/ or admixed with other ingredients, such as preservatives, stabilizers, protectivecolloids,

yulcanizing agents and the like.

It is obvious that numerous modifications and variations in the processes hereinabove described may be made Without'departing from the principles ofthis invention. It is our intention not to limit the claims hereof except as may be necessitated by the prior art. ,2

We claim:

1. The herein described method which comprises forming a homogeneous mixture .oflatex and an aqueous dispersion of a plasticized rubber, producing a formedarticle from said mixture, and drying and vulcanizing the said article" 1 v 1 ..2.-T.he herein described method which comprises preparing an. aqueous dispersion of a pl'asticized coagulated rubber, forminga homogeneous mixtureoflatex and said aque ous rubber dispersion, producing a formed article from said;mixture,- and drying and Vulcanizing said;artic-le.;,-- 7 '31 5 process which dispersing said rubber in fine particle size in an aqueous medium, forming ahomogeneousmixture of'latex and ,said aqueously dispersed rubber, producing a formed article from said mixture,-and drying and vulcanizing,thearticle.,-; F

.; 4l; The herein -sdescribed. process which lated rubber.

'6; JAs anew article of manufacture, avulcanized' rubber article comprlsingi a homogeneous admixture of unruptured latex globules, 'an'dlyfinely dispersed" particles. of masticated rubber; ;-1 V In Witness WllBIGOf'WS have hereunto set our hands this QLthfday of July, 1928.. x JAMES NV.SGHADE 1 HARLAN; L. TRUMBULL.

tended toI.-includetcaoutchou balata, gutta I 11 percha-and other;caoutchoucelike' substances, 

